Exogenous Ethylene Promotes the Germination of Cotton Seeds Under Salt Stress

Ethylene promotes seed germination under stress, but the optimum concentration and effect on cotton seeds under salt stress are unclear. In this paper, Nongdamian 601 seeds were used to identify the optimal ethephon (ethylene donor) concentration that promotes cotton seed germination, using 2-150-mM NaCl stress as the study range. The study also examined the effect and physiological characteristics at the optimal ethephon concentration to alleviate cotton seed germination under salt stress. At 150-mM NaCl stress, 2-mM ethephon treatment significantly increased the germination rate and germination potential of cotton seeds by 73.30 and 66.00%. At 7 days of germination, ethephon treatment reduced root length, surface area, and volume more than salt stress, but ethephon increased root diameter. Moreover, ethephon treatment significantly increased the contents of superoxide dismutase, peroxidase, proline, and soluble sugar of seeds than salt stress. Ethephon significantly increased the content of malondialdehyde. These results indicate that ethylene enhances the salt tolerance and germination rate of cotton seeds by enhancing the activity of antioxidant enzymes, increasing proline content, and alleviating the degree of membrane lipid peroxidation.